In what would be the biggest change yet to the way New York City’s school system is administered, officials are considering plans to hire private groups at taxpayer expense to manage scores of public schools.

The money paid to the private groups would replace millions of dollars in grants from the Bill and Melinda Gates Foundation, which supported dozens of these groups in opening more than 180 small schools in the city since 2003.

The four-year grants, typically worth $100,000 a year per school, will run out for more than 50 schools in June.

The move would further Chancellor Joel I. Klein’s earlier efforts to tear apart the traditional bureaucracy of the nation’s largest school system, giving principals greater autonomy and increasing the role of the private sector. It could put private entities like the College Board, the Urban Assembly and Expeditionary Learning-Outward Bound on contract to manage networks of schools as soon as the 2007-8 school year.

Although city officials stress that the plans are preliminary, they have been talking to the outside groups to gauge their interest. The proposal is already generating vigorous debate within the Education Department and among the outside groups over where to draw the line between public and private control of schools.

It is also certain to draw opposition from critics already questioning the school system’s reliance on private consultants as well as the educational credentials of outside groups. State law will also pose heavy obstacles to such contracts, officials in Albany said.

The private management plan is among a few options the department is weighing in an effort to formalize, and finance, its relationship with groups that are already helping run individual schools. While the groups have heavy influence over how children learn — recruiting staff, training teachers and offering an array of other support — their work is done on a handshake.

Under the new arrangement, the groups would oversee the schools and be held responsible for their results. They would be locked into contract terms and could be fired if student achievement lags.

Kristen Kane, Mr. Klein’s chief of staff, said the department considered the groups crucial to the early success of the new schools. “What happens to that success when there is no more private money?” she asked. “Will there be more private money or will we need to explore other ways to continue this partnership if we believe that is a critical success factor?”

Ms. Kane and other officials said they were also exploring the possibility of new private grants, or negotiating with the City Council to pay the groups with public money, allowing them to continue their work without expanding their authority.

“The conversations have been continuing with all of these organizations,” Ms. Kane said.

Marie Groark, a spokeswoman for the Gates Foundation, said that the grants to help start schools were not intended for renewal and that New York City had not asked for more money. “Our funding is devised to be catalytic, but long-term sustainability requires public support,” she said.

Randi Weingarten, the teachers’ union president, urged the administration to make its discussions more public. “I have been concerned about the sub rosa debate on whether to privatize the management of the school system for quite a while,” she said. “On an issue that is this transcendent there has to be a real public debate.”

One of the most hotly debated questions is whether the city would hire profit-making companies like Edison Schools Inc., which manages more than 20 schools in Philadelphia and has expressed interest in bidding on a city contract.

In 2001, an effort by Chancellor Harold O. Levy to hire Edison to run five failing schools collapsed after educators complained and furious parents voted it down.

Such opposition, to even the nonprofit groups, is likely to rise again. “Can you imagine these people picking what they want to do in instruction?” said a veteran education official who asked not to be identified, fearing retribution for not supporting the chancellor’s agenda. “They don’t know what they are doing.”

The educator added: “This is a way to crush public education. This is not a way to improve a school system.”

Do you want unaccountable people teaching your children? Well, that's what Mayor Mike is proposing. One more step to place oversight of the schools in smaller and smaller hands. It also helps to break the union. New York teachers make 20-30 percent less than suburban teachers. If private companies depress wages even further, who will become a teacher?

You already have problems with private fiefdoms in the public school system. This would codify them and allow the increasing fragmentation of the school system.

But the reality is that the new Democratic administration in Albany is going to be loathed to challenge their powerful union teacher friends. In fact, expect the charter school program to be revised sharply because of issues over teacher pay. The unions are going to demand a much smaller differential.

And Sharpton's opposition to a private company as consultants presages a greater struggle over private control of public resources. There is no great demand for this, and no evidence that it works better than public education.